Proven Wrong
by Yucho
Summary: As Frisk makes their way through Waterfall, they come across Sans, sleeping at his post. They figure this might be a good chance to do something nice for him. They are friends, after all... Undertale Friendship Fluff.


As Frisk made their way through Waterfall, they had to try not to lose their focus – Undyne could be anywhere. Even so, it was difficult to not be impressed. It all seemed so different. The strange blue light illuminating the cavern, The Echo Flowers recording conversations from who knows how long ago… It was all so otherworldly.

And yet it wasn't. This had all been here for Frisk's entire life. For the entire life of everyone they knew, down here or on the surface. These people had been trapped down here a long time, and that thought bothered the human. The Underground was a cool place, sure, even beautiful at times. But Frisk was already catching fleeting glimpses of the Castle that they'd be able to get home from. This much was obvious – It wasn't a big place. Part of Frisk was enjoying exploring it, but to spend their entire life down here… That would get old. To put it lightly.

They were lost in thought about that sort of stuff, until they caught a glimpse of something up ahead. They approached cautiously, but relaxed as they noticed what it was. It was Sans, asleep behind a sentry post. Frisk smiled slightly as they made their way up to him, treading carefully so as not to wake him, and stopping just in front of him.

They had to admit, their first instinct was to pull some kind of prank, but nothing came to mind. Nothing that Sans wouldn't get them back for, at least. Besides… It was kind of weird, and maybe Frisk was just imagining it, but Sans seemed to be a bit… On edge around them. He was perfectly friendly, but Frisk couldn't shake the feeling that Sans didn't trust them, or kept his guard up around them, at least.

It was probably just their imagination. They hadn't given Sans any reason not to trust them, after all – They hadn't hurt anyone since they'd fallen down here, and they weren't about to start. Frisk thought for a second. Maybe Sans just had trouble trusting people… Maybe they could help by doing something nice for him!

Frisk smiled as they got an idea. They took out a CinnaBun they'd bought in Snowdin and set it on the sentry post, next to the sleeping skeleton. It had been a nice surprise when Toriel had left them that slice of pie while they were sleeping, maybe Sans would enjoy that too.

They stepped back, looking at him with a frown. They were remembering a conversation the two of them had had in Snowdin Forest.

_"__Aren't you cold?" Frisk had asked, concerned about how Sans was only wearing shorts and (for some reason) slippers to walk through the snow._

_"__Huh?" Sans had replied, seeming tickled by the question. "Nah. Don't worry about me, kid. Town's not far now."_

'You look chilled to the bone.' Frisk suddenly thought, laughing quietly to themselves and wishing they'd thought of that one at the time. Granted, it wasn't as cold in Waterfall, but it was still nice to be warm. Frisk thought again for a second, fiddling with the scarf Toriel had given them before they'd left the Ruins, before slowly taking it off and draping it on the back of Sans' head, being careful not to wake him up.

Frisk stepped back. Hopefully, that wold help him be a bit more comfortable. They were sure he'd give them the scarf back too. They'd… Rather not lose that.

They smiled to themselves and started walking off, but then stopped. The temptation was too much. They took a piece of paper from their pocket and hastily wrote the word 'NUMBSKULL' on it, then discreetly taped it to Sans' back, laughing quietly again.

Then they kept moving. After a moment, however, something strange happened. Frisk turned their head, and noticed something soft. They went to touch it, and realised their scarf was suddenly back around their neck again. They looked back. Sure enough, it wasn't on Sans anymore. They looked around, but couldn't see or hear anyone else. If there was someone else, they probably wouldn't have focussed on giving Frisk their scarf back anyway.

The human stared at Sans for a moment. There was more to him than he let on, that much was obvious. But after thinking for a moment, Frisk decided that was fine. Sans wasn't going to get any reason to do anything drastic from them, and besides, he was Frisk's friend, and Frisk trusted him. Silently thanking him, Frisk continued on.

But only a few more seconds, and they noticed something on their back. Reaching back to grab it, they swiftly realised what it was. The word 'NUMBSKULL' was still right there, but below it was written something new. 'Nice try, kid.' Frisk grinned curiously at the message, impressed but mystified, and turned back to look at Sans. The skeleton still seemed to be fast asleep, and Frisk turned back, chalking it up to another thing Sans could just… Do.

Then they noticed something else on the back of the paper. 'Thanks though.' Frisk smiled, glad that their efforts were appreciated, and continued along their way, more of a spring in their step.

Once he was sure Frisk wouldn't turn around again, Sans opened one eye a tiny bit to watch them leave. He was here to watch out for them, sure, but he had to admit, he'd been worried about what kind of person they would be. Still, it was obvious by now that he had nothing to worry about. Not from them, at least. This human had shown him more than once now the kindness he hadn't dared hope for, and he couldn't help but crack a smile, a real smile, at the thought.

He'd been wrong about them.

**Authors Note:**

Well, here's something different! Apologies to anyone expecting another PMD story, I just got into an Undertale mood and felt like writing this. I'm also rather aware that there's probably a fair amount of stories like this, but hey, if you like that kind of stuff, I hope you enjoyed this too!

I should probably also mention I got the original idea for this story from an animation I saw on Tumblr a little while ago. I can't find it now, which is annoying, but it showed various characters leaving Sans gifts while he was sleeping. I found the idea really nice, so I wrote this!

I'm hoping my next story will be PMD, so if you like that sort of thing, keep an eye out! Don't know if I'll write more Undertalgie stuff. I might do a Deltarune story at some point, but I guess we'll see what happens!


End file.
